National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce
Current conditions at

Islip, Long Island Mac Arthur Airport (KISP)

Lat: 40.79°NLon: 73.1°WElev: 98ft.

Mostly Cloudy

72°F

22°C

Humidity 76%
Wind Speed NW 7 mph
Barometer 29.83 in (1009.8 mb)
Dewpoint 64°F (18°C)
Visibility 10.00 mi
Last update 12 Aug 6:56 am EDT
Extended Forecast for

Stony Brook NY

  • Today

    Today: A 20 percent chance of showers before 8am. Partly sunny, then gradually becoming sunny, with a high near 85. North wind around 6 mph becoming light and variable in the afternoon.

    High: 85 °F

    Slight Chance
    Showers then
    Sunny

  • Tonight

    Tonight: A 30 percent chance of showers and thunderstorms, mainly between 2am and 5am. Increasing clouds, with a low around 72. Southwest wind around 6 mph.

    Low: 72 °F

    Slight Chance
    T-storms then
    Chance
    Showers

  • Thursday

    Thursday: A chance of showers before 11am, then a slight chance of showers and thunderstorms after 2pm. Partly sunny, with a high near 84. West wind 5 to 7 mph. Chance of precipitation is 30%.

    High: 84 °F

    Chance
    Showers then
    Slight Chance
    T-storms

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 67. Southwest wind around 5 mph becoming light and variable.

    Low: 67 °F

    Partly Cloudy

  • Friday

    Friday: Mostly sunny, with a high near 82. North wind around 6 mph.

    High: 82 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 66.

    Low: 66 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 80.

    High: 80 °F

    Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 66.

    Low: 66 °F

    Mostly Clear

  • Sunday

    Sunday: A 30 percent chance of showers after 2pm. Mostly sunny, with a high near 82.

    High: 82 °F

    Mostly Sunny
    then Chance
    Showers

Detailed Forecast

Today
A 20 percent chance of showers before 8am. Partly sunny, then gradually becoming sunny, with a high near 85. North wind around 6 mph becoming light and variable in the afternoon.
Tonight
A 30 percent chance of showers and thunderstorms, mainly between 2am and 5am. Increasing clouds, with a low around 72. Southwest wind around 6 mph.
Thursday
A chance of showers before 11am, then a slight chance of showers and thunderstorms after 2pm. Partly sunny, with a high near 84. West wind 5 to 7 mph. Chance of precipitation is 30%.
Thursday Night
Partly cloudy, with a low around 67. Southwest wind around 5 mph becoming light and variable.
Friday
Mostly sunny, with a high near 82. North wind around 6 mph.
Friday Night
Mostly clear, with a low around 66.
Saturday
Sunny, with a high near 80.
Saturday Night
Mostly clear, with a low around 66.
Sunday
A 30 percent chance of showers after 2pm. Mostly sunny, with a high near 82.
Sunday Night
Showers likely, mainly after 8pm. Mostly cloudy, with a low around 69. Chance of precipitation is 70%.
Monday
A 30 percent chance of showers. Partly sunny, with a high near 83.
Monday Night
Partly cloudy, with a low around 67.
Tuesday
Sunny, with a high near 83.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Stony Brook NY
 40.92°N 73.15°W (Elev. 36 ft)
Last Update:
2:24 am EDT Aug 12, 2026
Forecast Valid:
7am EDT Aug 12, 2026-6pm EDT Aug 18, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation